Japan and Yokohama F. Marinos striker Tatsuhiko Kubo has been hit by the recurrence of lower back pain, which could deal a severe blow to the national side's World Cup preparations.
F Marinos officials said Kubo complained of pain after Tuesday's practice session and took a rest Wednesday without going to a hospital for either examinations or treatment.
"I heard the pain is too acute for him to even move and he intends to receive treatment after becoming able to move around," Yokohama manager Takeshi Okada told reporters.
The latest injury setback for Kubo comes at a time when Japan coach Zico has developed greater confidence in him after the lanky striker scored three goals in the last three matches for the national team.
Kubo earned a recall from Zico in late January after back and other injuries kept him out of action for his country well over a year. He replied by scoring the opening goal in Japan's 2-0 win over Finland in a home friendly and added two against India in an Asian Cup qualifier last month.
The 29-year-old took his form into the new J. League season, heading home a brace in F Marinos' 4-1 win over promoted Kyoto Purple Sanga in their season opener on Sunday.